😀 Intro
Hi, in this post, we will use Libvirt with Terraform to provision 2 KVM locally and after that, we will Deploy Flask App & PostgreSQL using Ansible.
Content
- Project Architecture
- Requirements
- Create KVM
Create Ansible Playbook
- Playbook to install Docker
- Playbook to install and configure postgresql
- Playbook to deploy Flask App
- Run Playbook and testing
- Conclusion
📝 Project Architecture
So we will create 2 VMs using Terraform, then deploying a Flask project and the database using Ansible.
🔨 Requirements
I used Ubuntu 22.04 LTS as the OS for this project. If you're using a different OS, please make the necessary adjustments when installing the required dependencies.
The major pre-requisite for this setup is KVM hypervisor. So you need to install KVM in your system. If you use Ubuntu you can follow this step:
sudo apt -y install bridge-utils cpu-checker libvirt-clients libvirt-daemon qemu qemu-kvm
Execute the following command to make sure your processor supports virtualisation capabilities:
$ kvm-ok
INFO: /dev/kvm exists
KVM acceleration can be used
Install Terraform
wget -O - https://apt.releases.hashicorp.com/gpg | sudo gpg --dearmor -o /usr/share/keyrings/hashicorp-archive-keyring.gpg
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/hashicorp-archive-keyring.gpg] https://apt.releases.hashicorp.com $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/hashicorp.list
sudo apt update && sudo apt install terraform -y
Verify installation:
$ terraform version
Terraform v1.9.8
on linux_amd64
Install Ansible
sudo apt update
sudo apt install software-properties-common
sudo add-apt-repository --yes --update ppa:ansible/ansible
sudo apt install ansible -y
Verify installation:
$ ansible --version
ansible [core 2.15.1]
...
Create KVM
we will use the libvirt provider with Terraform to deploy a KVM Virtual Machine.
Create main.tf, just specify the provider and version you want to use:
terraform {
required_providers {
libvirt = {
source = "dmacvicar/libvirt"
version = "0.8.1"
}
}
}
provider "libvirt" {
uri = "qemu:///system"
}
Thereafter, run terraform init command to initialize the environment:
$ terraform init
Initializing the backend...
Initializing provider plugins...
- Reusing previous version of hashicorp/template from the dependency lock file
- Reusing previous version of dmacvicar/libvirt from the dependency lock file
- Reusing previous version of hashicorp/null from the dependency lock file
- Using previously-installed hashicorp/template v2.2.0
- Using previously-installed dmacvicar/libvirt v0.8.1
- Using previously-installed hashicorp/null v3.2.3
Terraform has been successfully initialized!
You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.
If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.
Now create our variables.tf. This variables.tf file defines inputs for the libvirt disk pool path, the Ubuntu 20.04 image URL as OS for the VMs , and a list of VM hostnames.
variable "libvirt_disk_path" {
description = "path for libvirt pool"
default = "default"
}
variable "ubuntu_20_img_url" {
description = "ubuntu 20.04 image"
default = "https://cloud-images.ubuntu.com/releases/focal/release/ubuntu-20.04-server-cloudimg-amd64.img"
}
variable "vm_hostnames" {
description = "List of VM hostnames"
default = ["vm1", "vm2"]
}
Let's update our main.tf:
resource "null_resource" "cache_image" {
provisioner "local-exec" {
command = "wget -O /tmp/ubuntu-20.04.qcow2 ${var.ubuntu_20_img_url}"
}
}
resource "libvirt_volume" "base" {
name = "base.qcow2"
source = "/tmp/ubuntu-20.04.qcow2"
pool = var.libvirt_disk_path
format = "qcow2"
depends_on = [null_resource.cache_image]
}
resource "libvirt_volume" "ubuntu20-qcow2" {
count = length(var.vm_hostnames)
name = "ubuntu20-${count.index}.qcow2"
base_volume_id = libvirt_volume.base.id
pool = var.libvirt_disk_path
size = 10737418240 # 10GB
}
data "template_file" "user_data" {
count = length(var.vm_hostnames)
template = file("${path.module}/config/cloud_init.yml")
}
data "template_file" "network_config" {
count = length(var.vm_hostnames)
template = file("${path.module}/config/network_config.yml")
}
resource "libvirt_cloudinit_disk" "commoninit" {
count = length(var.vm_hostnames)
name = "commoninit-${count.index}.iso"
user_data = data.template_file.user_data[count.index].rendered
network_config = data.template_file.network_config[count.index].rendered
pool = var.libvirt_disk_path
}
resource "libvirt_domain" "domain-ubuntu" {
count = length(var.vm_hostnames)
name = var.vm_hostnames[count.index]
memory = "1024"
vcpu = 1
cloudinit = libvirt_cloudinit_disk.commoninit[count.index].id
network_interface {
network_name = "default"
wait_for_lease = true
hostname = var.vm_hostnames[count.index]
}
console {
type = "pty"
target_port = "0"
target_type = "serial"
}
console {
type = "pty"
target_type = "virtio"
target_port = "1"
}
disk {
volume_id = libvirt_volume.ubuntu20-qcow2[count.index].id
}
graphics {
type = "spice"
listen_type = "address"
autoport = true
}
}
the script will provisions multiple KVM VMs using the Libvirt provider. It downloads an Ubuntu 20.04 base image, clones it for each VM, configures cloud-init for user and network settings, and deploys VMs with specified hostnames, 1GB memory, and SPICE graphics. The setup dynamically adapts based on the number of hostnames provided in var.vm_hostnames.
As I've mentioned, I'm using cloud-init, so lets setup the network config and cloud init under the config directory:
mkdir config/
Then create our config/cloud_init.yml, just make sure that you configure your public ssh key for ssh access in the config:
#cloud-config
runcmd:
- sed -i '/PermitRootLogin/d' /etc/ssh/sshd_config
- echo "PermitRootLogin yes" >> /etc/ssh/sshd_config
- systemctl restart sshd
ssh_pwauth: true
disable_root: false
chpasswd:
list: |
root:cloudy24
expire: false
users:
- name: ubuntu
gecos: ubuntu
groups:
- sudo
sudo:
- ALL=(ALL) NOPASSWD:ALL
home: /home/ubuntu
shell: /bin/bash
lock_passwd: false
ssh_authorized_keys:
- ssh-rsa AAAA...
And then network config, in config/network_config.yml:
version: 2
ethernets:
ens3:
dhcp4: true
Our project structure should look like this:
$ tree
.
├── config
│ ├── cloud_init.yml
│ └── network_config.yml
├── main.tf
└── variables.tf
Now run a plan, to see what will be done:
$ terraform plan
data.template_file.user_data[1]: Reading...
data.template_file.user_data[0]: Reading...
data.template_file.network_config[1]: Reading...
data.template_file.network_config[0]: Reading...
...
Plan: 8 to add, 0 to change, 0 to destroy
And run terraform apply to run our deployment:
$ terraform apply
...
null_resource.cache_image: Creation complete after 10m36s [id=4239391010009470471]
libvirt_volume.base: Creating...
libvirt_volume.base: Creation complete after 3s [id=/var/lib/libvirt/images/base.qcow2]
libvirt_volume.ubuntu20-qcow2[1]: Creating...
libvirt_volume.ubuntu20-qcow2[0]: Creating...
libvirt_volume.ubuntu20-qcow2[1]: Creation complete after 0s [id=/var/lib/libvirt/images/ubuntu20-1.qcow2]
libvirt_volume.ubuntu20-qcow2[0]: Creation complete after 0s [id=/var/lib/libvirt/images/ubuntu20-0.qcow2]
libvirt_domain.domain-ubuntu[1]: Creating...
...
libvirt_domain.domain-ubuntu[1]: Creation complete after 51s [id=6221f782-48b7-49a4-9eb9-fc92970f06a2]
Apply complete! Resources: 8 added, 0 changed, 0 destroyed
Verify VM creation using virsh command:
$ virsh list
Id Name State
----------------------
1 vm1 running
2 vm2 running
Get instances IP address:
$ virsh net-dhcp-leases --network default
Expiry Time MAC address Protocol IP address Hostname Client ID or DUID
-----------------------------------------------------------------------------------------------------------------------------------------------
2024-12-09 19:50:00 52:54:00:2e:0e:86 ipv4 192.168.122.19/24 vm1 ff:b5:5e:67:ff:00:02:00:00:ab:11:b0:43:6a:d8:bc:16:30:0d
2024-12-09 19:50:00 52:54:00:86:d4:ca ipv4 192.168.122.15/24 vm2 ff:b5:5e:67:ff:00:02:00:00:ab:11:39:24:8c:4a:7e:6a:dd:78
Try to access the vm using ubuntu user:
$ ssh [email protected]
The authenticity of host '192.168.122.15 (192.168.122.15)' can't be established.
ED25519 key fingerprint is SHA256:Y20zaCcrlOZvPTP+/qLLHc7vJIOca7QjTinsz9Bj6sk.
This key is not known by any other names
Are you sure you want to continue connecting (yes/no/[fingerprint])? yes
Warning: Permanently added '192.168.122.15' (ED25519) to the list of known hosts.
Welcome to Ubuntu 20.04.6 LTS (GNU/Linux 5.4.0-200-generic x86_64)
...
ubuntu@ubuntu:~$
Create Ansible Playbook
Now let's create the Ansible Playbook to deploy Flask & Postgresql on Docker. First you need to create ansible directory and ansible.cfg file:
$ mkdir ansible && cd ansible
[defaults]
inventory = hosts
host_key_checking = True
deprecation_warnings = False
collections = ansible.posix, community.general, community.postgresql
Then create inventory file called hosts:
[vm1]
192.168.122.19 ansible_user=ubuntu
[vm2]
192.168.122.15 ansible_user=ubuntu
checking our VMs using ansible ping command:
$ ansible -m ping all
192.168.122.15 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}
192.168.122.19 | SUCCESS => {
"ansible_facts": {
"discovered_interpreter_python": "/usr/bin/python3"
},
"changed": false,
"ping": "pong"
}
Now create playbook.yml and roles, this playbook will install and configure Docker, Flask and PostgreSQL:
---
- name: Deploy Flask
hosts: vm1
become: true
remote_user: ubuntu
roles:
- flask
- config
- name: Deploy Postgresql
hosts: vm2
become: true
remote_user: ubuntu
roles:
- psql
- config
Playbook to install Docker
Now create new directory called roles/docker:
$ mkdir roles
$ mkdir docker
Create a new directory in docker called tasks, then create new file main.yml. This file will install Docker & Docker Compose:
$ mkdir docker/tasks
$ vim main.yml
---
- name: Run update
ansible.builtin.apt:
name: aptitude
state: latest
update_cache: true
- name: Install dependencies
ansible.builtin.apt:
name:
- net-tools
- apt-transport-https
- ca-certificates
- curl
- software-properties-common
- python3-pip
- virtualenv
- python3-setuptools
- gnupg-agent
- autoconf
- dpkg-dev
- file
- g++
- gcc
- libc-dev
- make
- pkg-config
- re2c
- wget
state: present
update_cache: true
- name: Add Docker GPG apt Key
ansible.builtin.apt_key:
url: https://download.docker.com/linux/ubuntu/gpg
state: present
- name: Add repository into sources list
ansible.builtin.apt_repository:
repo: deb [arch=amd64] https://download.docker.com/linux/ubuntu {{ ansible_lsb.codename }} stable
state: present
filename: docker
- name: Install Docker
ansible.builtin.apt:
name:
- docker-ce
- docker-ce-cli
state: present
update_cache: true
- name: Add non-root to docker group
user:
name: ubuntu
groups: [docker]
append: true
- name: Install Docker module for Python
ansible.builtin.pip:
name: docker
- name: Install Docker-Compose
ansible.builtin.get_url:
url: https://github.com/docker/compose/releases/download/1.29.2/docker-compose-Linux-x86_64
dest: /usr/local/bin/docker-compose
mode: '755'
- name: Create Docker-Compose symlink
ansible.builtin.command:
cmd: ln -s /usr/local/bin/docker-compose /usr/bin/docker-compose
creates: /usr/bin/docker-compose
- name: Restart Docker
ansible.builtin.service:
name: docker
state: restarted
enabled: true
Playbook to install and configure postgresql
Then create new directory called psql, create subdirectory called vars, tempalates & tasks:
$ mkdir psql
$ mkdir psql/vars
$ mkdir psql/templates
$ mkdir psql/tasks
After that, in vars, create main.yml. These are variables used to set username, passwords, etc:
---
db_port: 5433
db_user: admin
db_password: dbPassword
db_name: todo
Next, we will create jinja file called docker-compose.yml.j2. With this file we will create postgresql container:
version: '3.7'
services:
postgres:
image: postgres:13
container_name: db
restart: unless-stopped
ports:
- {{ db_port }}:5432
networks:
- flask_network
environment:
- POSTGRES_USER={{ db_user }}
- POSTGRES_PASSWORD={{ db_password }}
- POSTGRES_DB={{ db_name }}
volumes:
- postgres_data:/var/lib/postgresql/data
networks:
flask_network:
volumes:
postgres_data:
Next, create main.yml to tasks. So we will copy docker-compose.yml.j2 and run using docker compose:
---
- name: Add Postgresql Compose
ansible.builtin.template:
src: docker-compose.yml.j2
dest: /home/ubuntu/docker-compose.yml
mode: preserve
- name: Docker-compose up
ansible.builtin.shell: docker-compose up -d --build
args:
chdir: /home/ubuntu
Playbook to deploy Flask App
First, you need to create directory called flask, then create sub-directory again:
$ mkdir flask
$ mkdir flask/vars
$ mkdir flask/templates
$ mkdir flask/tasks
Next, add main.yml to vars. This file refer to posgtresql variable before, with addition IP address of VM2(database VM):
---
db_port: 5433
db_user: admin
db_password: dbPassword
db_name: todo
db_host: 192.168.122.15
Next, create config.py.j2 to templates. This file will replace the old config file from Flask project:
DEV_DB = 'sqlite:///task.db'
pg_user = "{{ db_user }}"
pg_pass = "{{ db_password }}"
pg_db = "{{ db_name }}"
pg_port = {{ db_port }}
pg_host = "{{ db_host }}"
PROD_DB = f'postgresql://{pg_user}:{pg_pass}@{pg_host}:{pg_port}/{pg_db}'
Next, create docker-compose.yml.j2 to templates. With this file we will create a container using docker compose:
version: '3.7'
services:
flask:
build: flask
container_name: app
restart: unless-stopped
ports:
- 5000:5000
environment:
- DEBUG=0
networks:
- flask_network
networks:
flask_network:
Next, create main.yml in tasks. With this file we will clone flask project, add compose file, replace config.py and create new container using docker compose:
---
- name: Clone html project
changed_when: false
ansible.builtin.git:
repo: https://github.com/danielcristho/Flask_TODO.git
dest: /home/ubuntu/Flask_TODO
clone: true
- name: Add Flask Compose
ansible.builtin.template:
src: docker-compose.yml.j2
dest: /home/ubuntu/Flask_TODO/docker-compose.yml
mode: preserve
- name: Update config.py
ansible.builtin.template:
src: config.py.j2
dest: /home/ubuntu/Flask_TODO/flask/app/config.py
mode: preserve
- name: Run docker-compose up -d
shell: docker-compose up -d --build
args:
chdir: /home/ubuntu/Flask_TODO
Our project structure should look like this:
├── ansible-flask-psql
│ ├── ansible.cfg
│ ├── hosts
│ ├── playbook.yml
│ └── roles
│ ├── docker
│ │ └── tasks
│ │ └── main.yml
│ ├── flask
│ │ ├── tasks
│ │ │ └── main.yml
│ │ ├── templates
│ │ │ ├── config.py.j2
│ │ │ └── docker-compose.yml.j2
│ │ └── vars
│ │ └── main.yml
│ └── psql
│ ├── tasks
│ │ └── main.yml
│ ├── templates
│ │ └── docker-compose.yml.j2
│ └── vars
│ └── main.yml
├── libvirt-kvm
│ ├── config
│ │ ├── cloud_init.yml
│ │ └── network_config.yml
│ ├── main.tf
│ ├── variables.tf
Run Playbook and testing
Finally, let's run ansible-playbook to deploy PostgreSQL and Flask:
$ ls
ansible.cfg hosts playbook.yml roles
$ ansible-playbook -i host playbook.yml
_____________________
< PLAY [Deploy Flask] >
---------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
________________________
< TASK [Gathering Facts] >
------------------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| |
...
____________
< PLAY RECAP >
------------
\ ^__^
\ (oo)\_______
(__)\ )\/\
||----w |
|| ||
192.168.122.15 : ok=13 changed=3 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
192.168.122.19 : ok=15 changed=4 unreachable=0 failed=0 skipped=0 rescued=0 ignored=0
After complete, just make sure there is no error. Then you see there are two created. In VM1 is Flask and VM2 is Postgresql:
$ docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS
NAMES
f3978427e34c flask_todo_flask "python run.py" About a minute ago Up About a minute 0.0.0.0:5000->5000/tcp, :
::5000->5000/tcp app
$ docker ps
fbebdff75a6e postgres:13 "docker-entrypoint.s…" 4 minutes ago Up 4 minutes 0.0.0.0:5433->5432/tcp, [::]:5433
->5432/tcp db
Try to access the app using browsers, just type http://<vm1_ip>:
Try to add a new task and then the data will be added to the database:
Conclusion
Finally, thank you for reading this article. Feel free to leave a comment if you have any questions, suggestions, or feedback.
Nb: Project Repo: danielcristho/that-i-write
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